Injection efficiency of DI and CTIA readout integrated circuit

Advanced hybrid infrared focal plane arrays (IRFPA) consist of a semiconductor photodetector chip which is bump-bonded to a silicon CMOS readout integrated circuit (ROIC) chip generally containing a reset integrator preamp to accumulate detector photon-induced current over a fixed integration time. A number of readout structures have been developed for different system applications and concerns, among which the direct injection (DI) and the capacitor feedback transimpedance amplifier (CTIA) are popularly used. The structures and performances, especially injection efficiency, of DI and CTIA are respectively discussed and compared. The DI enables an ultralow power consumption and has a high injection efficiency at large background photocurrent, while the CTIA has a comparatively higher power dissipation and higher injection efficiency at low background photocurrent.